Involvement of IL-6 in the anti-human immunodeficiency virus activity of IFN-tau in human macrophages

Preemptive interleukin-6 blockade in patients with COVID-19

Excessive interleukin-6 signaling is a key factor contributing to the cytokine release syndrome implicated in clinical manifestations of COVID-19. Preliminary results suggest that tocilizumab, a humanized monoclonal anti-interleukin-6 receptor antibody, may be beneficial in severely ill patients, but no data are available on earlier stages of disease. An anticipated blockade of interleukin-6 might hypothetically prevent the catastrophic consequences of the overt cytokine storm. We evaluated early-given tocilizumab in patients hospitalized with COVID-19, and identified outcome predictors. Consecutive patients with initial Sequential-Organ-Failure-Assessment (SOFA) score < 3 fulfilling pre-defined criteria were treated with tocilizumab. Serial plasma biomarkers and nasopharyngeal swabs were collected. Of 193 patients admitted with COVID-19, 64 met the inclusion criteria. After tocilizumab, 49 (76.6%) had an early favorable response. Adjusted predictors of response were gender, SOFA score, neutrophil/lymphocyte ratio, Charlson comorbidity index and systolic blood pressure. At week-4, 56.1% of responders and 30% of non-responders had cleared the SARS-CoV-2 from nasopharynx. Temporal profiles of interleukin-6, C-reactive protein, neutrophil/lymphocyte ratio, NT-ProBNP, D-dimer, and cardiac-troponin-I differed according to tocilizumab response and discriminated final in-hospital outcome. No deaths or disease recurrences were observed. Preemptive therapy with tocilizumab was safe and associated with favorable outcomes in most patients. Biological and clinical markers predicted outcomes.

Characterization of Simian Immunodeficiency Virus Variants Anatomically Compartmentalized in Plasma and Milk in Chronically Infected African Green Monkeys

Unlike human immunodeficiency virus type 1 (HIV-1)-infected humans, African-origin, natural simian immunodeficiency virus (SIV) hosts, such as African green monkeys (AGMs), sustain nonpathogenic SIV infections and rarely vertically transmit SIV to their infants. Interestingly, chronically SIV-infected AGMs have anatomically compartmentalized SIV variants in plasma and milk, whereas humans and SIV-infected rhesus monkeys (RMs), Asian-origin nonnatural SIV hosts, do not exhibit this compartmentalization. Thus, it is possible that AGM SIV populations in milk have unique phenotypic features that contribute to the low postnatal transmission rates observed in this natural host species. In this study, we explored this possibility by characterizing the infectivity, tropism, and neutralization susceptibility of plasma and milk SIVsab env variants isolated from chronically SIVsab92018ivTF-infected AGMs. AGM plasma and milk SIVsab env pseudovirus variants exhibited similar infectivities, neutralization susceptibilities to autologous and heterologous plasma, and chemokine coreceptor usages for cell entry, suggesting similar abilities to initiate infection in a new host. We also assessed the cytokine milieu in SIV-infected AGM milk and compared it to that of SIV-infected RMs. MIP-1β, granulocyte colony-stimulating factor (G-CSF), interleukin-12/23 (IL-12/23), and IL-13 trended significantly higher in SIV-infected AGM milk than in that of RMs, while IL-18 and IL-6 trended significantly higher in SIV-infected RM milk than in that of AGMs. Taken together, our findings imply that nonviral maternal factors, such as the cytokine milieu, rather than unique characteristics of SIV populations in the milk contribute to the low postnatal transmission rates observed in AGMs.

IMPORTANCE

Due to the ongoing global incidence of pediatric HIV-1 infections, including many that occur via breastfeeding, development of effective vaccine strategies capable of preventing vertical HIV transmission through breastfeeding remains an important goal. Unlike HIV-1-infected humans, African green monkeys (AGMs), the natural SIV host species, sustain nonpathogenic SIV infections, rarely transmit the virus postnatally to their infants, and exhibit anatomically compartmentalized SIV populations in milk and plasma. Identifying unique features of the anatomically compartmentalized milk SIV populations could enhance our understanding of how AGMs may have evolved to avoid transmission through breastfeeding. While this study identified limited phenotypic distinctions between AGM plasma and milk SIV populations, potential differences in milk cytokine profiles of natural and nonnatural SIV hosts were observed. These findings imply the potential importance of nonviral factors in natural SIV host species, such as innate SIV/HIV immune factors in milk, as a means of naturally preventing vertical transmission.

Bovine Viral Diarrhea Virus Type 2 Impairs Macrophage Responsiveness to Toll-Like Receptor Ligation with the Exception of Toll-Like Receptor 7

Bovine viral diarrhea virus (BVDV) is a member of the Flaviviridae family. BVDV isolates are classified into two biotypes based on the development of cytopathic (cp) or non-cytopathic (ncp) effects in epithelial cell culture. BVDV isolates are further separated into species, BVDV1 and 2, based on genetic differences. Symptoms of BVDV infection range from subclinical to severe, depending on strain virulence, and may involve multiple organ systems and induction of a generalized immunosuppression. During BVDV-induced immune suppression, macrophages, critical to innate immunity, may have altered pathogen recognition receptor (PRR) signaling, including signaling through toll-like receptors (TLRs). Comparison of BVDV 2 strains with different biotypes and virulence levels is valuable to determining if there are differences in host macrophage cellular responses between viral phenotypes. The current study demonstrates that cytopathic (cp), noncytopathic (ncp), high (hv) or low virulence (lv) BVDV2 infection of bovine monocyte-derived macrophages (MDMΦ) result in differential expression of pro-inflammatory cytokines compared to uninfected MDMΦ. A hallmark of cp BVDV2 infection is IL-6 production. In response to TLR2 or 4 ligation, as might be observed during secondary bacterial infection, cytokine secretion was markedly decreased in BVDV2-infected MDMΦ, compared to non-infected MDMΦ. Macrophages were hyporesponsive to viral TLR3 or TLR8 ligation. However, TLR7 stimulation of BVDV2-infected MDMΦ induced cytokine secretion, unlike results observed for other TLRs. Together, these data suggest that BVDV2 infection modulated mRNA responses and induced a suppression of proinflammatory cytokine protein responses to TLR ligation in MDMΦ with the exception of TLR7 ligation. It is likely that there are distinct differences in TLR pathways modulated following BVDV2 infection, which have implications for macrophage responses to secondary infections.

Vaginal innate immune mediators are modulated by a water extract of Houttuynia cordata Thunb

Background

Vaginal epithelial cells (VECs) produce antimicrobial peptides including human β-defensin 2 (hBD2) and secretory leukocyte protease inhibitor (SLPI), as well as cytokines and chemokines that play vital roles in mucosal innate immunity of the female reproductive tract. Houttuynia cordata Thunb (H. cordata), a herbal plant found in Asia, possesses various activities including antimicrobial activity and anti-inflammation. As inflammation and infection are commonly found in female reproductive tract, we aimed to investigate the effects of H. cordata water extract in modulating innate immune factors produced by VECs.

Methods

Primary human VECs were cultured and treated with H. cordata at a concentration ranging from 25–200 μg/ml for 6 or 18 h. After treatment, the cells and culture supernatants were harvested. The expression of hBD2 and SLPI mRNA was evaluated by quantitative real-time reverse transcription PCR. Levels of secreted hBD2 and SLPI as well as cytokines and chemokines in the supernatants were measured by ELISA and Luminex assay, respectively. Cytotoxicity of the extract on VECs was assessed by CellTiter-Blue Cell Viability Assay.

Results

H. cordata did not cause measurable toxicity on VECs after exposure for 18 h. The expression of hBD2 and SLPI mRNA as well as the secreted hBD2 protein were increased in response to H. cordata exposure for 18 h when compared to the untreated controls. However, treatment with the extract for 6 h had only slight effects on the mRNA expression of hBD2 and SLPI. The secretion of IL-2 and IL-6 proteins by VECs was also increased, while the secretion of CCL5 was decreased after treatment with the extract for 18 h. Treatment with H. cordata extract had some effects on the secretion of IL-4, IL-8, CCL2, and TNF-α, but not statistically significant.

Conclusions

H. cordata water extract modulates the expression of antimicrobial peptides and cytokines produced by VECs, which play an important role in the mucosal innate immunity in the female reproductive tract. Our findings suggest that H. cordata may have immunomodulatory effects on the vaginal mucosa. Further studies should be performed in vivo to determine if it can enhance mucosal immune defenses against microbial pathogens.

Houttuynia cordata modulates oral innate immune mediators: potential role of herbal plant on oral health

OBJECTIVE

Epithelial cells play an active role in oral innate immunity by producing various immune mediators. Houttuynia cordata Thunb (H. cordata), a herbal plant found in Asia, possesses many activities. However, its impacts on oral innate immunity have never been reported. The aim of this study was to determine the effects of H. cordata extract on the expression of innate immune mediators produced by oral epithelial cells.

MATERIALS AND METHODS

Primary gingival epithelial cells (GECs) were treated with various concentrations of the extract for 18 h. The gene expression of hBD2, SLPI, cytokines, and chemokines was measured using quantitative real-time RT-PCR. The secreted proteins in the culture supernatants were detected by ELISA or Luminex assay. Cytotoxicity of the extract was assessed using CellTiter-Blue Assay.

RESULTS

H. cordata significantly induced the expression of hBD2, SLPI, IL-8, and CCL20 in a dose-dependent manner without cytotoxicity. The secreted hBD2 and SLPI proteins were modulated, and the levels of IL-2, IL-6, IL-8, and IFN-γ were significantly induced by the extract.

CONCLUSIONS

Our data indicated that H. cordata can modulate oral innate immune mediators. These findings may lead to the development of new topical agents from H. cordata for the prevention and treatment of immune-mediated oral diseases.

Interferon-tau attenuates uptake of nanoparticles and secretion of interleukin-1β in macrophages

BACKGROUND

Type I interferons (IFNs), including IFN-alpha (IFNA) and IFN-beta (IFNB), have anti-inflammatory properties and are used to treat patients with autoimmune and inflammatory disorders. However, little is known of the role of IFN-tau (IFNT), a type I IFN produced by ruminant animals for inflammation. Because IFNB has recently been shown to inhibit nucleotide-binding oligomerization domain-like receptor, pyrin domain-containing 3 (NLRP3) inflammasome activation and subsequent secretion of the potent inflammatory cytokine interleukin (IL)-1β, we examined the effects of ruminant IFNT on NLRP3 inflammasome-mediated IL-1β secretion in human THP-1 macrophages.

METHODS AND RESULTS

IFNT dose-dependently inhibited IL-1β secretion induced by nano-silica, a well-known activators of NLRP3 inflammasomes, in human macrophages primed with lipopolysaccharide (LPS, TLR4 agonist) and Pam3CSK4 (TLR1/2 agonist). IFNT also suppressed phagocytosis of nano-silica and reactive oxygen species (ROS) generation. Western blot analysis showed that IFNT inhibited both pro-IL-1β and mature IL-1β. In addition, real-time RT-PCR analysis showed that IFNT suppressed IL-1β mRNA expression induced by LPS and Pam3CSK4. Although nano-silica particles did not induce IL-10 secretion, IFNT induced IL-10 secretion in a dose-dependent manner. Furthermore, IFNT-suppressed IL-1β secretion was restored by anti-IL-10 neutralizing antibody.

CONCLUSIONS

Ruminant IFNT inhibits NLRP3 inflammasome-driven IL-1β secretion in human macrophages via multiple pathways, including the uptake of nano-silica particles, generation of ROS, and IL-10-mediated inhibition of pro-IL-1β induction. It may be a therapeutic alternative to IFNA and IFNB.

Interferon-tau: current applications and potential in antiviral therapy

Interferon-tau (IFN-tau) was initially identified as an ovine pregnancy protein. Produced by the trophoblast, it is important in preventing degradation of the corpus luteum and has been used as an early marker for ovine pregnancy. As a member of the family of type I interferons, IFN-tau has demonstrated promising antiviral activity against human viral infections in vitro. Additionally, it displays high species cross-reactivity despite its absence in humans. To date, IFN-tau has shown efficacy in reducing replication of human immunodeficiency virus, feline immunodeficiency virus, and human papillomavirus. While IFN-tau shares similar antiviral activity to IFN-alpha, the current interferon of choice for treatment of viral infections, it lacks the associated toxicity. This may make IFN-tau an attractive alternative to IFN-alpha for the treatment of viral infections.

HIV-1 and the macrophage

Macrophages and CD4+ T cells are natural target cells for HIV-1, and both cell types contribute to the establishment of the viral reservoir that is responsible for continuous residual virus replication during antiretroviral therapy and viral load rebound upon treatment interruption. Scientific findings that support a critical role for the infected monocyte/macrophage in HIV-1-associated diseases, such as neurological disorders and cardiovascular disease, are accumulating. To prevent or treat these HIV-1-related diseases, we need to halt HIV-1 replication in the macrophage reservoir. This article describes our current knowledge of how monocytes and certain macrophage subsets are able to restrict HIV-1 infection, in addition to what makes macrophages respond less well to current antiretroviral drugs as compared with CD4+ T cells. These insights will help to find novel approaches that can be used to meet this challenge.

Effect of type-I interferon on retroviruses

Type-I interferons (IFN-I) play an important role in the innate immune response to several retroviruses. They seem to be effective in controlling the in vivo infection, though many of the clinical signs of retroviral infection may be due to their continual presence which over-stimulates the immune system and activates apoptosis. IFN-I not only affect the immune system, but also operate directly on virus replication. Most data suggest that the in vitro treatment with IFN-I of retrovirus infected cells inhibits the final stages of virogenesis, avoiding the correct assembly of viral particles and their budding, even though the mechanism is not well understood. However, in some retroviruses IFN-I may also act at a previous stage as some retroviral LTRs posses sequences homologous to the IFN-stimulated response element (ISRE). When stimulated, ISREs control viral transcription. HIV-1 displays several mechanisms for evading IFN-I, such as through Tat and Nef. Besides IFN-α and IFN-β, some other type I IFN, such as IFN-τ and IFN-ω, have potent antiviral activity and are promising treatment drugs.